The purpose of the Lexicon of Geospatial Terminology is to provide a common set of geospatially-related terms and concepts in order to encourage consistent use of terminology and promote a clearer understanding of the commonly used terms.  A common, but living, lexicon that meets logical and taxonomic standards is vital to achieving the goals of the Geospatial LoB and represents the first step in conforming all documents and discussions to a common vocabulary.

This lexicon builds upon existing concepts and provides a point of reference for OMB Circular A–16 reporting.  The relationship of the lexicon to the Federal Enterprise Architecture (FEA) is also described.

<Add explanation of what the lexicon wiki is and how it works.>

This is an evolving and expanding list of terms and definitions related to the geospatial community that will expand and change over time.   To suggest changes, additions, and deletion please visit the moderated forum for the lexicon <add link here>. 

<Link to the lexicon wiki>

 Background and Context of the Lexicon of Geospatial Terminology

In OMB Circular A–16, a single term is sometimes used to represent multiple concepts, which can cause confusion.  The data context portion of the Federal Enterprise Architecture (FEA) Data Reference Model includes a framework that was developed to address such problems.  The FEA Consolidated Reference Model defines data context as “a standard approach to representing taxonomies that an agency uses to categorize its data.  Such categorization enables the business context of data to be well understood.” To develop the Lexicon of Geospatial Terminology included here, the concepts and glossary of OMB Circular A–16 were adapted using this approach. Ongoing modifications of the lexicon will also use this approach.

Topics included in the current lexicon are limited to and consistent with those included in the FEA Business Reference Model (BRM).  Although non-Federal stakeholder BRMs will be considered as sources for future topics, most future topics are expected to be derived from the nineteen lines of business that are included under the service to citizens component of the FEA BRM.

Topics belong to subfunctional areas under a BRM from which an entity might derive one or more themes.  Each theme, in turn, is composed of one or more datasets.  Datasets are the actual logical and physical representations of geographic features.  As of this writing, all the potential or existing datasets that might make up the National Spatial Data Infrastructure (NSDI) have not yet been identified.  The Lexicon of Geospatial Terminology formalizes the hierarchy of topics, themes, and datasets.  Currently, there is no concept to capture potential “themes” that are not currently part of OMB Circular A–16.  To define possible themes not presently included in the list in OMB Circular A–16, appendix E, the authors chose the word “topic,” which is consistent with the FEA Data Reference Model.  The figure below portrays the hierarchy of topics, themes, and datasets and the relationship of topics to themes. It also provides examples of topics and themes, how they flow from BRMs, and how one might use NSDI geospatial data principles or other guidelines to discover candidate A–16 themes.

B.2 Hierarchy of topics and themes, and the relationship of topics to themes.
Terms used: BRM, Business Reference Model; FDA, Food and Drug Administration; FEA, Federal Enterprise Architecture; USDA, U.S. Department of Agriculture

Terms and definitions relevant to the management of A–16 themes are scattered among various key documents, including OMB Circular A–16, FGDC standards, International Organization for Standardization (ISO) standards, U.S. statutes and administrative laws, the FEA Geospatial Profile Version 2.0, the Geospatial LoB Common Solutions and Common Architecture (CSTA) (published under the Geospatial Line of Business March 2006 and redacted August 2007),  and various data calls.  The Lexicon of Geospatial Terminology incorporates, synthesizes, and resolves the differences among concepts when there are duplicates or conflicts.  Every effort was made to recognize existing standards or commonly accepted definitions among the Geospatial LoB representatives.  Where standardized definitions were not available, final definitions were determined by consensus among the Geospatial LoB Lifecycle Management Work Group members.

Geospatial Terminology Categories and Terms

A common, but living, lexicon that meets logical and taxonomic standards is vital to achieving the goals of the Geospatial LoB and represents the first step in conforming all documents and discussions to a common vocabulary.  The major categories for geospatial terminology include the following:

• Information (INF)
• Data services (DSV)
• Program management (PMT)
• Geospatial (GEO)
• General services (GSV)
• Geospatial information system services(GIS)
• Data analysis/data services (DAS)
• GIS needs assessment (GNA)
• OMB Circular A–16 data themes (A–16)
• National Spatial Data Infrastructure data themes (NDT)
• Geospatial One-Stop data communities (GOS)
• FEA Geospatial Profile V2, Appendix B: Glossary of Terms (FEA)
• Department of Homeland Security Homeland Security Presidential Directive-7 sectors (DHS)